Development of semi-industrial synthesis of calcium polysulfide solution and determination of the content of sulfide ions in solution

Semi-industrial synthesis of a calcium polysulfide solution, a good demercurizing reagent in the technology for utilization of mercury-containing wastes, was developed. The development of a technology for utilization of wastes of this kind with the use of a calcium polysulfide solution is primarily associated with choosing the Hg: CaS n ratios. The Hg: CaS n ratio was found from the concentration of sulfide ions in the CaS n solution because the composition of the CaS n solution, where n = 4–6, is not constant. A photocolorimetric method was developed for determining the concentration of sulfide ions in the CaS n solution. The method was used for rapidly finding the content of sulfide ions in the CaSn solution on batches of industrial solutions in refinement of the technology for waste demercurization. The results obtained in determining the content of sulfide ions in a CaS n solution were confirmed by the independent titrimetric method.